1. Field of the Invention
This invention relates generally to pile cutting and crushing apparatus and methods, and more particularly, to an apparatus and method for shearing reinforced concrete piles, metal piles, casing and conductor pipe arrangements, and crushing reinforced concrete piles to expose reinforcing steel within the piling without damaging the structural integrity of the imbedded steel.
2. Background Art
As used herein, the term “columnar” is defined as resembling or having the form of a column. The term “pile” or “piling”, as used herein, means a long columnar member driven or installed into the earth or seabed to carry a vertical load or serve as a support or protection. The present invention has utility in the construction industry for shearing and crushing reinforced concrete piles or pilings, and in the offshore oil and gas well drilling industry for shearing metal piles that are used to anchor and support offshore platforms, and the associated well casing and conductor pipe arrangements, including conductor arrangements having concentric sleeved pipes with grout or cementation in the annulus between adjacent pipes, when decommissioning or demolishing offshore platforms.
In the construction industry, reinforced concrete piles, prefabricated pre-stressed concrete piles, auger bore piles, as well as drill shaft piles are used as vertical supporting members for supporting highway overpasses, bridges, docks and piers. During a demolition or construction contract, the removal of existing piles or pilings or the cutting and/or crushing of newly installed piling to a desired elevation may become necessary to complete a project.
Several common methods for removal of existing pilings of the type used in supporting highway overpasses, bridges, docks and piers include the use of hydraulic vibrators, mechanical crushing jaws, concrete saws, jackhammers and cutting torches and mechanical cutters. These procedures are time consuming and costly.
One method commonly employed involves the contractor saw cutting the perimeter of the pile at a specific elevation, to a depth just beyond the depth of the steel strands imbedded within the pile, usually 2 to 3 inches below the pile surface, and then, breaking the pile off at this point. This method is slow and labor intensive when multiple piles are involved. When the exposure of the steel reinforcing strands or bars (rebar) within the piles is specified, the task of exposing the rebar is typically accomplished by jack hammering and chiseling, which requires extensive man-hours, with potential danger to the operator, depending on the location of the piles, and damage to the steel reinforcing by the jackhammer or chipping tool.
Reinforced concrete piles are also conventionally cut off or demolished using explosives, however, the use of explosives, particularly in demolishing bridge, pier and dock supporting piles, can have serious negative environmental effects encompassing the water environment and the marine life that typically congregate near piles and utilize the structures as a natural habitat.
Several mechanical cutting devices have been designed and patented in the past twenty-five years that employ the use of hydraulic rams to cause the leading edge of a cutting blade to penetrate and sever various materials. Dating as far back as the 1950's, this method was utilized to cut trees for removal as well as severing the tree into usable lengths.
More recently, this basic design has been employed for the purpose of cutting concrete piles. For example Trudeau, U.S. Pat. No. 5,139,006, discloses a hydraulic pile cutter apparatus and method. In a single blade embodiment, the apparatus is leveled about the pile to be cut, and the blade is pushed through the reinforced concrete pile until it nearly reaches an opposed stationary plate to sever the top of the pile, including the reinforcements. In a double blade embodiment having a fixed blade opposed to a coplanar movable blade, both blades have cutting edges formed to fit around the pile, and the double blades shear the concrete of the pile leaving the reinforcement intact. Projecting vertical angle iron attachments for shattering the concrete above the common plane and recessed attachments for pile guiding are also disclosed.
Trudeau, U.S. Pat. No. 5,245,982, discloses a hydraulic concrete pile cutter apparatus and method which utilizes a single blade with a beveled cutting edge which confronts a stationary anvil plate having a substantially flat abutment face supporting a concrete pile on the side opposite the blade. The blade has a substantially straight cutting edge and is driven through the pile to crack the concrete matrix of the pile and into edge-to-face engagement with the abutment face of the anvil throughout the length of the cutting edge to sever the reinforcement strands. The blade may be provided with a wedge-shaped cutting edge wherein driving the blade into the concrete matrix of the pile wedges the matrix apart at the selected position. An alternative anvil may be mounted on the anvil gate, which includes a back plate with an abutment face for supporting the pile at the cut-off location and against which the blade engages when fully extended. The alternative anvil also includes two supports above and below the abutment face, each consisting of two wedge-shaped elements projecting from the face of the plate to form angular support surfaces that match and support three adjacent faces of a hexagonal pile, such that of the six corners on the hexagonal pile, four are supported by the anvil and the other two are at edges of the pile that is first engaged with the cutting blade.
Trudeau, U.S. Pat. No. 5,413,086, discloses a method and apparatus for preparing an end of a reinforced concrete pile which utilizes a shear blade having a straight cutting edge to sever the top of a pile supported on the flat abutment surface of a stationary anvil plate opposite the blade. Once the top of the pile has been cut off, the shear blade and anvil are replaced with a pair of coplanar blades each having a cutting edge that matches the profile of one-half of the pile for removing the concrete matrix from the reinforcement strands down to a certain level below the cutoff position. The coplanar blades engage the surface of the pile and penetrate the surface while wedging the upper part of the pile up away from the main body of the pile to crack the concrete through at the desired position. At the same time, upright angle iron concrete breaker attachments mounted on the blades engage the concrete pile above the blades to fracture the concrete from the reinforcing steel.
The above noted patents employ a “blade and anvil method” for severing the pile and reinforcement strands which utilizes a straight cutting blade having a beveled cutting edge to sever the piling by forcing the straight cutting edge of the cutting blade through the pile until it is in full “edge-to-face” contact with the opposing flat anvil surface, thus severing the piling and the structural steel reinforcing therein between the blade edge and the face of the abutment/anvil surface. The above noted patents also teach replacing the shearing blade and anvil with a pair of coplanar blades each having a cutting edge that matches the profile of one-half of the pile that engage the surface of polygonal piles and penetrate the surface while wedging the upper part of the pile up away from the main body of the pile to crack the concrete through at the desired position, and fracture the concrete from the reinforcing steel with concrete breakers mounted on the blades.
The prior art blade and anvil “edge-to-face” cutting method and pile crushing method, such as described in the above patents, have several drawbacks. The blade and anvil “edge-to-face” method requires that the straight cutting blade edge make full and complete contact with the face of the anvil surface to complete the cut. As the straight beveled edge of the cutting blade becomes worn, it prevents the leading edge of the blade from making complete contact with the anvil face, thus potentially preventing the leading edge of the blade from completely severing all the steel strands and/or rebar. One of the problems with the prior art pile crushing method, such as taught by these patents, is that it requires the removal of the shearing blade and the anvil abutment plate and the installation of a pair of opposed coplanar blades each having a cutting edge that matches the profile of one-half of the pile; thus, different sizes of coplanar blades would be required for crushing various different sizes and shapes of piles to achieve the desired result.
In the offshore oil and gas well drilling industry, offshore marine structures or platforms are supported on and anchored to the ocean floor by “piles” which are hollow casings or pipes driven into the sea bed. These offshore structures typically include “casing” or “conductor” arrangements that extend from deep into the sea floor up to the production deck of the offshore structure which are used in drilling and as conduits to carry petroleum and gas from a reservoir deep within the earth to a gathering and process location on the offshore structure above the sea floor and also above the surface of the sea. These casing or conductor arrangements are typically composed of several concentric sleeved pipes of increasing diameters with the space between the side walls of the pipes being filled with grout or reinforcing cementation.
When the wells serviced by the platform run dry, the offshore platforms must be “decommissioned” or removed and appropriately disposed of. Current regulations require that when removing an offshore platform, all structural elements of the platform and all well conductors (both the piles and conductors) must be removed down to a depth of at least 15 feet below the mud line so that no projections are left which could pose a navigational hazard or present an obstacle to mariners, unless a special exception is granted. The principal basis for an exception is using the platform in a rigs-to-reefs program administered by the state of Louisiana or Texas, whereby some platforms are deposited at designated sites to provide a habitat for reef fish that are valued by recreational and commercial fishermen.
Current methods for decommissioning or removing offshore platforms include the use of mechanical cutters, such as saws and water jet cutters driven from the surface, and explosives. However, conventional mechanical cutting procedures are time consuming and expensive. If there is concrete or grout between the casing and conductor or in the annulus between the pipes, the cutting is slowed down and the cutter may not work efficiently.
In a typical conventional mechanical cutting operation, a cutting tool is placed inside of the casing and/or conductor and is rotated to make the cut from inside the casing. When the first inside casing is removed, another cutter with a greater diameter is placed inside of the conductor and it is cut in the same manner as the casing. If there is concrete or grout between the casing and conductor or in the annuals formed by the two pipes, the cutter may not function properly. If the casing cannot be cut from the inside, it must be cut from the outside. When cutting the casing and conductor or pile to a depth of at least fifteen-feet below the sea floor, a hole must be excavated around the casing and conductor or pile to allow a diver to enter into the excavation with sufficient room to cut the casing and conductor or pile off. The conventional mechanical cutting operations and use of divers is time consuming, expensive, and dangerous to the divers.
The use of explosives is often used for the removal of grouted well conductors or grouted piles, however, this technique can have serious deleterious environmental effects encompassing the marine environment and the living marine resources, such as sea turtles, marine mammals, and fish, that typically congregate near the platform and utilize the platform as a natural habitat.
European Patent EP 0243981 discloses a method and a cutting tool for cutting-off an elongate marine platform pile made up of steel cylinders filled with concrete and located one inside the other. The apparatus has a frame and a cutting blade slidably mounted thereon which is moved by hydraulic cylinders toward a counterpiece which may be fixed to the frame in opposed relation to the blade in a plane below the plane of the cutter blade, or may be pivotally mounted on the frame. As viewed from the top, the blade has a wide V-shaped leading edge. As seen from the side, the upper face of the blade consists of two inclined planes that intersect at the edge of the blade, and the bottom surface of the blade is horizontal. The cutting blade is pressed against the pile, which is supported against the counterpiece. A cutting force is directed at the pile by means of the cutting edge of the blade, which has a larger blade angle (larger than 45°, preferably 65° to 75° with respect to a horizontal plane), and a bending force is directed at the pile by means of a wedge effect of the smaller inclination angle (smaller than 45°, preferably about 30° to 40° with respect to a horizontal plane). A crack is formed in the pile in front of the blade edge, and the pile is broken by the bending moment. The wide V-shaped edge causes a shearing effect to be directed at the pile first at two points, and as cutting continues, the sides of the pile are cut before the middle part of the pile. In this device the blade tends to move upwards when the cutting is started and, to prevent breaking the frame, the face of the counterpiece is mounted at a small angle (about 1° to 5° with respect to a vertical plane) such that the counterpiece can turn downwards while the blade is rising.
The present invention overcomes the several disadvantages, drawbacks or deficiencies of the prior art reinforced concrete pile cutting and crushing apparatus and methods in that it provides an apparatus and method that employs a “shearing method” to cut concrete piles containing reinforcement steel, wherein the leading edge of the movable cutting blade does not make contact with the anvil face or surface, as opposed to the blunt edge-to-face “blade and anvil” cutting method of the prior art. The present invention also employs a concrete pile crushing method that does not require the removal of the primary cutting blade, as required in prior art methods, but instead, utilizes the same cutting blade that was used in the shearing operation for the crushing operation with the addition of a set of crushing attachments. Any size piling that can be cut by the shearing operation can be crushed with the addition of the crushing attachments Thus, the present pile cutting and crushing apparatus and method requires less servicing time when converting from the cutting operation to the crushing operation, and eliminates the need for several sizes of crushing jaws. The present crushing apparatus and method also crushes concrete material surrounding the reinforcing steel in the piling to expose the steel reinforcing within, without damaging the integrity of the structural steel within the pile.
The present invention also overcomes the several disadvantages, drawbacks or deficiencies of the prior art devices that cut metal pipe and piles used to support offshore platforms, and the associated casing and concentric conductor pipe arrangements, in that it provides an apparatus and method that employs a balanced shearing action to cut the metal members wherein one side of the metal pile is supported against a pair of vertically spaced stationary abutment surfaces and shearing surfaces in a plane above and below the plane of the leading edge the cutter blade and the leading edge of the cutting blade passes horizontally through the metal pile and continues through the vertically spaced abutment surfaces and shearing surfaces, thereby significantly reducing ovate distortion of the pile, the tendency of the blade to rise or move upwards or downwards during cutting and the resultant offset stress forces on the frame and blade.
Removable crushing attachments allow the same frame and blade apparatus used for the shearing operation to be used for crushing reinforced concrete piles, and removable concave abutment attachments adapt the apparatus to accommodate cylindrical piles, casing, tubing and conductor pipes, and significantly reduces ovate deformation during the shearing operation.